Study On The Preparation And Properties Of The Composite Natural Rubber Based Latex With Nano-SiO₂, Silk Fibroin And Amphiphilic Copolymers

Natural rubber latex is a renewable polymeric material displaying excellent physical properties. Because of the good film forming ability, the natural rubber latex-dipped products have been widely used in heath care and electronic areas. Although natural rubber possesses many superior properties, it lacks in some properties such as oil resistance, some soluble proteins in natural rubber products can cause seriously allergy. Consequently, modification of natural rubber is much needed to overcome the disadvantages. In this paper, the mechanical properties and oil resistance of natural rubber latex films could be improved by using heterocoagulation of natural rubber latex with silk fibroin, silk fibroin/silica composite and synthesized copolymers, respectively. The modification of natural rubber with lower extractable protein content was also studied.Silk fibroin is an abundant, stable and biocompatible material. As blending with natural rubber latex, due to the interaction between silk fibroin and the water soluble proteins on the outer layer of the natural rubber latex paticle, the solidification mechanism of natural rubber latex have changed so that the modified natural rubber latex films would have excellent mechanical property with reduced water soluble proteins. Silica coated silk fibroin composites were further prepared by using two methods, blending method and the sol-gel method. The experimental results showed that the film modified by blending method prepared silk fibroin/silica composites had a better performance compared with composites by the sol-gel method. As to blending method prepared silk fibroin/silica composites, the composites had a core-shell structure, with silk fibroin as the core and silica as the shell. After blending with natural rubber latex, the composites can form a layer on rubber particle with a thickness of0.5μm-1μm. The films modified by the composites resulted in an increase of the mechanical properties and the enrichment of hydrophilic substance on the film surface had also been decreased. The water vapor permeance tests showed that the modified films became more compactness. While modified natural rubber latex with the sol-gel method prepared silk fibroin/silica composites, the hydrophilicity of the film had been improved.The natural rubber latex films modified by poly(methyl methacrylate)(PMMA) have been reported, but the compatibility between PMMA and natural rubber is poor. Hence the copolymer poly(methyl methacrylate-co-acrylamide)(PMMA-co-PAM) were prepared through emulsion polymerization to improve the the compatibility between PMMA and natural rubber. Because of hydrophilic amide groups on the acrylamide molecular chain could easily interact with nonrubber components, the compatibility between PMMA and natural rubber was improved. Results indicated that the mechanical properties and oil resistance properties of the modified films had been improved significantly.